Deployment ICOM radio project

[allester666]

I have been tasked with setting up an ICOM radio system where I am currently deployed. I have some components, but not all of them.

I have 4 IC-FR3000 repeaters. They came with duplexers, but no instructions on how to use them. The duplexer is labeled with a TX value: 150,000, RX: 155,000. there are 3 n style connectors on the duplexers which are labeled low pass, antenna, and high pass. the back of the duplexer has 6 screws on it to connect wires to.

Question 1) How do I set up this duplexer effectively? I have no knowledge in this area, and having little luck with general internet research.

The repeaters did not come with antennas. The instructions for the unit say that the unit uses a 50 ohm antenna...real specific haha. Will an antenna (such as a jungle) using 50 ohm wire for the transmission line fulfill that need? For now, the radios need to cover about 5 square km, maybe further (40 km) in the future. I think an omni-directional antenna would work well here, initially for testing I will be using jungle antennas.

Question 2) What makes a jungle antenna a 50 ohm antenna? I read on electronics tutorials.com that the 45 degree down angle creates an artificial ground leading to an impedence of 50 ohms...but I don't understand how that works!

Question 3) Does anyone know what the corresponding default frequencies from the factory on a 16 channel ICOM F11 model are? No luck on researching that one so far. The radios did not come with programming cables/software, so I have to order those. The only thing I can think to do for now is plug in frequencies to an MBITR to see if i can talk to the icom.

Thanks to anyone who can help!

[no-hertz]

I am going to try an address some of your questions. Some of my answers are not very helpful I realized after typing them up, but could send you in a direction to find more answers. I am trying to pull up some documentation on your equipment and see what I can figure out about it. Do the duplexer's have a IC-xxxx model number?


I have been tasked with setting up an ICOM radio system where I am currently deployed. I have some components, but not all of them.

I have 4 IC-FR3000 repeaters. They came with duplexer's, but no instructions on how to use them. The duplexer is labeled with a TX value: 150,000, RX: 155,000. there are 3 n style connectors on the duplexer's which are labeled low pass, antenna, and high pass. the back of the duplexer has 6 screws on it to connect wires to.

Without seeing the Duplexer configuration, I can tell you that the antenna connection obviously goes to the antenna, and the high and low pass connectors go to the receiving and transmitting radio. I am unsure about the 6 post-terminals you are referring too.


Question 1) How do I set up this duplexer effectively? I have no knowledge in this area, and having little luck with general internet research.

This duplexer as it is configured can only be used if you use the frequencies listed on it. It may work slightly outside of those values, but will work in a degraded manner, if at all. You can also bypass using the duplexer for the time being by using two separate antenna's, separated by a fair amount of physical distance, 10+ feet for a 5+ MHz spread. A duplexer filters out all but a specific range of frequencies so that you cannot overload one duplexer has band-passes that are specifically tuned for particular frequencies. Whether or not your are tunable by the user I do not know. Tuning them is also a rather complex and delicate task.




The repeaters did not come with antennas. The instructions for the unit say that the unit uses a 50 ohm antenna...real specific haha. Will an antenna (such as a jungle) using 50 ohm wire for the transmission line fulfill that need? For now, the radios need to cover about 5 square km, maybe further (40 km) in the future. I think an omni-directional antenna would work well here, initially for testing I will be using jungle antennas.

What the manual means is that the radio needs a 50ohm impedance on the transmitting antenna, and other than that your antenna choice is pretty much up to you. Any antenna that can handle 50 Watts (what your repeater puts out) would be suitable, as long as it is tuned relatively to frequency, and does not have an insane SWR. There are plenty of VHF antenna's you can choose from, or depending on you OE you could construct your own as well.



Question 2) What makes a jungle antenna a 50 ohm antenna? I read on electronics tutorials.com that the 45 degree down angle creates an artificial ground leading to an impedance of 50 ohms...but I don't understand how that works!

This is a complex question that delves into physics, the way electrons move on a wire, the way radio-waves interact in free space, and real space, etc. I suggest Google-Fu and maybe a couple ARRL books on the subject.



Question 3) Does anyone know what the corresponding default frequencies from the factory on a 16 channel ICOM F11 model are? No luck on researching that one so far. The radios did not come with programming cables/software, so I have to order those. The only thing I can think to do for now is plug in frequencies to an MBITR to see if i can talk to the icom.


Without the spec's from Icom (try e-mailing them) your next easiest solution is a spectrum analyzer, key up the mic and hone in on the spike. I don't know where you are operating out of, but I would just mention that frequencies (EMSO)are managed by US forces as well as most host countries. Food for thought before you start "hi-jacking" frequencies. Also for repeater use, unless the radio's are pre-programmed with repeater offset channels instead of single channel simplex channels, those repeaters will not do you much good.


Erik

[Paragrouper]

Question 1) How do I set up this duplexer effectively? I have no knowledge in this area, and having little luck with general internet research.!

The six screws on the bottom of your duplexer (diplexer) are likely for mounting the unit. The only connections you need to concern yourself with are the N-type connectors; High-pass to transmit, low-pass to receive and the antenna is self-explanatory. No-Hertz, in his post was correct--you do not need to use the duplexer; just use two antennas. If you do, place one of the antennas above the other (at least three to six feet). If you place them side by side the two antennas will couple and you will have some serious interference problems.

I downloaded the manual from ICOM's technical support site, which also has email a phone contact information. PM me and I'll send you the link.

[alelks]

I downloaded the manual also and posted it to a site I own.

Here's the link: Manual (http://www.atvgraphics.org/Downloads/ic-fr3000_fr4000.pdf)

Here's the service manual: Service Manual (http://www.atvgraphics.org/Downloads/IC-FR3000_SM.pdf)

[allester666]

Thanks to all who have replied to this topic.

No-hertz, the model of the duplexer is IAS RDN 165A. I have a pic, but can't post...still need an admin to bless me off on QP status.

Thank you for the antenna advice...I will probably not use the duplexer's and set up two antenna's (plenty of speaker wire and 12 gauge copper wire laying around). Also, the service manual post was handy in case I do install the duplexers. I ran into an element here that has a spectrum analyzer, so I will be able to make some tests before my programming equipment comes. Thanks again for the help!

[allester666]

Was able to determine that the ICOMS come with a RX freq of 146.03 PT FM on channel 1 (factory), still trying to find the TX if someone could help that would be great! I talked with a guy that had a spectrum analyzer, who provided me with the freq...should have been the TX but its not working with an MBITR.

[no-hertz]

Was able to determine that the ICOMS come with a RX freq of 146.03 PT FM on channel 1 (factory), still trying to find the TX if someone could help that would be great! I talked with a guy that had a spectrum analyzer, who provided me with the freq...should have been the TX but its not working with an MBITR.

I am a little surprised by this. Most of those radios have a 25Khz step for analog and 12.5Khz step for digital if they have it.

146.03 seems weird to me. did you watch him do any of this, or did he just give you the info. Also, how do you know it is the RX freq, did you make one way commo, RX only?

have you tried transmitting from an MBITR, using different CTCSS tones? Some of those radio use tones by default as well, which is something you will not notice with a O-Scope. time consuming, but start at 67.0 and work your way up. I have a handy Yaesu VX-6R that will tone scan on it's own, but I imagine you don't have too many HAM radio's in your toolbox.

[allester666]

I am able to transmit from the MBITR to the ICOM on channel 1 at 146.03 MHz. This works in both FM and NB, and with any value entered in for CTCSS. I am yet unable to figure the freq/settings for RX from the ICOM to the MBITR. I am hoping this will be solved when I recieve the programming software/cables for the repeaters and individual ICOM RT's.

I am willing to try to make some antenna's that cover the 146-174 MHz range. I ordered a 5/8 wavelength TRAM antenna to see how it is constructed, hoping to learn a bit more about antenna theory and how to apply it a little bit further than the basics learned in the Q course. Does anyone have ideas/blueprints?

[no-hertz]

just out of curiosity have you tried 146.000 MHz?

I am still baffled that the carrier is on 146.03. obviously it is working for you, but just seems a rather odd center freq.

[Paragrouper]

just out of curiosity have you tried 146.000 MHz?

I am still baffled that the carrier is on 146.03. obviously it is working for you, but just seems a rather odd center freq.

Me too, especially since the specification in the manual (link above) state the bands of operation to be 148-172MHz or 150-174MHz depending on the version.

Have you tried contacting customer support?

[allester666]

The programming software/cables have arrived for both the radios and repeaters. Upon reading the radios default channels, I determined that channels 1 - 3 were pre-programmed at the factory. Channel 1's freq was set to 146.03. The radios operate between 146-174 according to the manual...so while its an number, it does match what was determined by a spectrum analyzer. I set the CTCSS tone to 150.0, and as before I am able to talk from the MBITR to the ICOM. I still unable to talk from ICOM to MBITR. This will not stop the project in its tracks, but it would be nice to have the option to have two way coms with the locals...I will continue to investigate this side of the problem.

I had ordered one VHF antenna, but it has yet to arrive. A second antenna will be needed if a duplexor is not used, which I prefer not to in this situation. I dont want to limit traffic to one TX/RX freq if the locals decide to set up a "backup channel" structure.

I have constructed 2 100ft cables made of RG213, with N style connectors to terminate to the repeaters, and PL259 connectors on the opposite side to terminate into the antenna's SO239 connection.

Still hoping someone can provide a good blue-print for a antenna in the 146-174 range! Any takers?

[no-hertz]

I will give you a couple links to get you started, but if you Google "2m ham antenna" there will be thousands of different sets of plans and variations on them that all the HAM guys use on 2 meters. Only a small adjustment to get up to your frequencies. 2m is technically 150Mhz, but due to FCC band allocation, resides between 144-147.99 Mhz.

http://home.comcast.net/~buck0/hampage.htm

http://www.ac6v.com/antprojects.htm

Most of the time I end up picking the antenna based on my available construction material.

Just a note, I have a couple 2m copper tubing J-Poles I use at home for shooting the shit on local repeaters, seem to work well for me.

[allester666]

No-hertz, your last reply was very helpful. The links you provided have steered me right in the direction I was looking for...I have a small bit of ladder line, and constructed the ladder line j-pole with RG213 as the transmission line. A bit of tweaking got me to 1:1.4 SWR...not bad for a 100ft transmission line (Eventually the antenna of choice will be going up in a radio tower). The solid copper wire 5/8 stack J-pole is my next project...just have to wait for the wire to arrive by mail and I'll be busy again. Thanks again for the help, this was exactly what I needed!!

[no-hertz]

glad to help out. I am active in amateur radio (when home) and probably the most enjoyable part for me is making antenna's, getting them working well, and just tinkering to stretch those watts a few more miles.

out of curiosity what are you using to measure your SWR, a field meter with a pass through style or an antenna analyzer ala MFJ-269 style?

[allester666]

I am using the MFJ-259B, kinda wishing I would have sprung for the 269 in case I start working with higher freqs!

[allester666]

Once again, thanks to all that have given input on this topic. I have done a ton of research on this subject, and based on the environment/cost/availability of raw materials I have constructed the 5/8 collinear J-pole antenna. I was able to easily tune the antenna to 1.1:1 SWR at the frequency i wanted using galvanized wire, pvc pipe, hose clamps and some coax cable. I chose galvanized wire for the environment, and based off of the past success of a HAM enthusiast.

The links previously provided had easy to follow instructions for constructing a 2M (146mhZ) antenna. Provided in the comment section was a design made by an enthusiast who decided to used steel over copper...what a great and unexpected result. I used hose clamps over circuit breaker connections, and achieved the same awesome 1.1:1 results with a slight bit of tuning. Great antenna, great comments, thank you all so much.

Please PM me with any requests regarding this subject.

[allester666]

I built the antennas, which are Double Stacked collinear J-poles. They tuned up GREAT, easy to do with parts from the city (all but the transmission lines that is). I was able to finally get MBITR/ICOM/repeater coms, with a ton of different guesses in the programming settings. Now if I could only tie in the older Motorola radios used by the police here....

A quick question for the SME's out there...can the repeater be set as the "base" and still function as a repeater? If not, then the local Comms Center will just have to operate off of an individual radio. Thanks for the help, wish I could get my QP status straight so i could post pictures...pm if you have any questions, and thanks for all the help!

[Paragrouper]

can the repeater be set as the "base" and still function as a repeater? If not, then the local Comms Center will just have to operate off of an individual radio.

I do not believe that is possible. The repeater operation will be full-duplex and the Base station operation would be simplex. I will make a call tomorrow to see what your options are.

[Paragrouper]

I do not believe that is possible. The repeater operation will be full-duplex and the Base station operation would be simplex. I will make a call tomorrow to see what your options are.

Contrary to my previous message, it seems that you should be able to to both.

I contacted ICOM America technical support, ( 425) 450-6087, and they left me a message stating that it should be as simple as hooking up the microphone. He further stated that when you transmit it will interrupt the repeater function until you finish transmitting.

I hope this helps.

[allester666]

Both antenna's are now bolted up in the 50ft tower. The antennas are 10 ft long...so i had them mounted so that the second antenna is 5 ft below the top of the other one. That means that they are on the same level for about five feet (bottom half of top one, and upper half of second one). I have conducted some radio checks from within the city, with mixed results. The base station reported that my transmissions came in very clear most of my check points except for at the police station (didn't hear me at all). I had another unit being monitored by a friend on duty indoors, and he was not able to hear my traffic about 2 km away from town.

I am wondering if I should try Yagi antennas? I figured a repeater pushing 50 watts of RF would have no problems!

[SF_BHT]

Both antenna's are now bolted up in the 50ft tower. The antennas are 10 ft long...so i had them mounted so that the second antenna is 5 ft below the top of the other one. That means that they are on the same level for about five feet (bottom half of top one, and upper half of second one). I have conducted some radio checks from within the city, with mixed results. The base station reported that my transmissions came in very clear most of my check points except for at the police station (didn't hear me at all). I had another unit being monitored by a friend on duty indoors, and he was not able to hear my traffic about 2 km away from town.

I am wondering if I should try Yagi antennas? I figured a repeater pushing 50 watts of RF would have no problems!

It may be the orientation of the antenna. We use antennas that are down looking for sites on mountains/hills. We have 90 deg side radiating antennas and then Yagi's to shoot up to interconnected repeaters. You need to put a antenna analyzer on your transmission line and check for loss at your connectors, Heliax cable and then check you antenna. All points are problems when you are using factory or home made systems.

[Paragrouper]

The distance between your antennas is likely an issue.

Because of their proximity, you are likely inserting noise into your receive path, which will reduce the range that your repeater can effectively receive incoming signals. this will also impact transmitted signals from the repeater, as the quality of the retransmitted signal may be degraded.

I suggest you try increasing the the vertical spacing between your antennas, which will increase the isolation between the receive and transmit paths. Also verify that your cables and connectors are correct, as shielding issues will exacerbate the problem.

Changing to a directional antenna array would help, but only if your desired coverage area lies within the effective beamwidth of the directional antenna.

[allester666]

I was kind of afraid of that answer, but knew it was coming:)

Guess I need to get a lineman's belt, and get up their and raise one of the antenna's. Do you think it would be sufficient to have the bottom of the top antenna level with the top of the lower one? I would like to keep the antenna's up as high as possible, but a previous post talked about keeping a few feet in vertical distance apart. Thanks again for the help...I wish i could post pictures of this project, I think you guys would like to see what I'm working with here!

[no-hertz]

Going with a Yagi setup would not be wise unless all of your operations were taking place in a specific, and somewhat narrow band away from your transmission location.

You are likely receiving well at the base station because of the height of the antenna, and are likely having problems with your re-transmit due to coupling of the antenna's in the near field. The antenna could also be coupling with the tower as well.

Getting the antenna's some physical separation is going to help a bit, and also as a thought if you have a tower, You could consider two different types of antenna's, like a dipole or inverted V using the top of the tower as a center support, and your folded antenna used to transmit mounted 10 feet down the tower, or even the inverse.

Hard to armchair quarterback your antenna setup without seeing it, and hell you probably don't need any armchair QB advice anyways. Sounds like you are getting a good setup built, just to iron out the damn kinks as always.

[Paragrouper]

Do you think it would be sufficient to have the bottom of the top antenna level with the top of the lower one? I would like to keep the antenna's up as high as possible, but a previous post talked about keeping a few feet in vertical distance apart.

My previous post, (3-6') was actually a somewhat of a compromise, given the importance of maintaining good height for the antennas. Try to keep some physical separation, as this vertical "stacking" makes the best use of the nulls in the radiation pattern to improve your isolation.

[allester666]

I was blessed with the availability of a communications testing team being available, and know the right guy to knudge them in our direction. The out come was amazing; to senior enlist NCO for them Marine Corp and Airforce that could speak to the locals, and were very knowledgabe about older systems and HAM/VHF systems. The gave me some critical guidance in getting the city covered, just one more week till we see the final results!

Learning what i did today, i know i will have to bring my RX antenna down to a resonable VSWR, and hoist it up higher in length.

[Paragrouper]

Learning what i did today, i know i will have to bring my RX antenna down to a resonable VSWR, and hoist it up higher in length.

It's good to hear you got some onsite assistance. Hopefully you will get things worked out this time. Perhaps when all is said and done you can post your lessons-learned, along with a good description of the final soluition to help others with a similar problem.

I am curious, your previous posts suggested that you had the antenna VSWR in order. What is it now?